with a bunch of comments on the nature and future disposition of
the data.

Signed-off-by: Sebastien Awwad <[email protected]>

Signed-off-by: Sebastien Awwad <[email protected]>

Signed-off-by: Sebastien Awwad <[email protected]>

Based on feedback from product, don't show message for unsigned metadata
but do show warm fuzzy message for correctly signed metadata.

Forgot a module path component when calling `load_metadata_from_file`

Use a catch-all block so failing to get a valid, updated `key_mgr.json`
doesn't cause conda to crash and burn.

Allow the user to configure the base URL to look for `*.root.json` and
`key_mgr.json`, rather than assuming these required files are in the
base directory of each channel (i.e., when `channeldata.json` lives).
This better fits how we anticipate deploying these files as the artifact
verification feature goes into production.

Protect against cases where the user has requested metadata signature
verification but no key manager trust metadata is available; e.g., a
user has turned this feature on for the first time, but no trust
metadata can be obtained for the repository they're using.

Package signing trust metadata should be publicly available and not
protected by a token; suppressing the existing authentication mechanisms
ensures users can obtain these trust metadata even when they've set the
`add_anaconda_token` conda configuration option to True.

These are actually an indication that no updates are available and are
not real errors.

Reflects name change of the `conda-authentication-resources` package to
`conda-content-trust`.

`conda build` currently does not allow packages to include empty
directories, so we may need to create `etc/conda` at runtime for storing
artifact verification metadata (`*.root.json`, `key_mgr.json`).

Also, separate `_refresh_*` operations into individual functions to
improve code clarity.

Prevent conda from crashing when `etc/conda` contains files whose names
end with `.root.json` but do not contain just digits in their prefix.

Switch to `from ... import ...` structure to reduce awkward looking
function names.